偏航姿态对北斗精密单点定位的影响分析

Impact Analysis of Yaw Attitude on BDS Precise Point Positioning

当太阳相对于卫星轨道面的高度角较小时,北斗导航卫星将不会跟踪太阳位置,卫星姿态发生异常复杂的变化后一段时间内处于零偏模式。在此期间采用名义姿态将影响卫星天线相位中心偏差、相位缠绕等误差计算,进而使精密单点定位(PPP)参数估计和天顶对流层延迟估计出现偏差。研究表明,在北斗导航卫星处于零偏期间,采用名义姿态计算的相位缠绕、天线相位中心偏差中存在超过15cm的误差。在此期间的北斗卫星采用零偏姿态改正相位缠绕等误差,与采用名义姿态相比,动态PPP位置参数N、E、U的估计精度可以提高53.2%、54.2%、39.3%,静态PPP位置参数N、E、U的估计精度可以提高61.0%、72.3%、58.4%,天顶对流层延迟估计精度提高33.0%。

When the elevation of the Sun with respect to orbital plane is small, the BDS satellite will not track the position of sun and thus will lead to abnormal attitude changing. To avoid this phenomenon, the satellite attitude keeps in orbit-normal mode during the period. The nominal attitude correction methods will affect the calculation of antenna phase center offset and phase wind-up in orbit-normal seasons, and furthermore lead to biases to the position and zenith tropospheric delay（ZTD） estimatedby precise point positioning （PPP）. The results of the experiments undergone show that the comprehensive phase wind-up and the satellite antenna phase center errors caused by the incorrect BDS satellite orbit model will exceed 15 cm. Compared to the nominal attitude mode, when the orbit-normal attitude mode is adopted, the positioning accuracy in the north,east and up directions will be improved by 53.2%,54.2%,and 39.3% for dynamic PPP, 61. 0% , 72. 3% , 58. 4% for static PPP, respectively. Furthermore, the accuracy of ZTD estimated by static PPP will be improved by 33.0%.